From: Chandra Seetharaman <sekharan@us.ibm.com>
Date: Thu, 13 Nov 2008 23:39:00 +0000 (+0000)
Subject: dm mpath: avoid attempting to activate null path
X-Git-Tag: v2.6.28-rc5~17^2~3
X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?p=linux-2.6-omap-h63xx.git;a=commitdiff_plain;h=b81aa1c79201cb424114fd198607951900babe18

dm mpath: avoid attempting to activate null path

Path activation code is called even when the pgpath is NULL. This could
lead to a panic in activate_path(). Such a panic is seen in -rt kernel.

This problem has been there before the pg_init() was moved to a
workqueue.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 4840733cd90..58b1015260f 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -441,13 +441,13 @@ static void process_queued_ios(struct work_struct *work)
 		__choose_pgpath(m);
 
 	pgpath = m->current_pgpath;
-	m->pgpath_to_activate = m->current_pgpath;
 
 	if ((pgpath && !m->queue_io) ||
 	    (!pgpath && !m->queue_if_no_path))
 		must_queue = 0;
 
-	if (m->pg_init_required && !m->pg_init_in_progress) {
+	if (m->pg_init_required && !m->pg_init_in_progress && pgpath) {
+		m->pgpath_to_activate = pgpath;
 		m->pg_init_count++;
 		m->pg_init_required = 0;
 		m->pg_init_in_progress = 1;